Process for rendering polyurethane foams hydrophilic by reacting same with a lactone



United States Patent 3,413,245 PROCESS FOR RENDERING POLYURETHANE FOAMSHYDROPHILIC BY REACTING SAME WITH A LACTONE Joerg Sambeth and AlexisArchipotf, both 0 Carouge, Switzerland No Drawing. Continuation-impartof application Ser. No.

332,250, Dec. 20, 1963. This application Jan. 31, 1967, Ser. No. 612,824

Claims. (Cl. 260-) ABSTRACT OF THE DISCLOSURE A method of rendering apolyester or polyether based polyurethane foam hydrophilic is set forthwhich comprises (1) reacting at a temperature of from about 70 to 110 C.in the presence of a catalyst selected from the group consisting ofpotassium hydroxide, sodium hydroxide, potassium chloride, potassiumacetate, potassium phenolate, potassium methylate and potassiumisopropylate (a) a polyether or polyester based polyurethane foam and(b) at least one carboxylic hydroxyacid lactone having the generalformula wherein R R and R are selected from the group consisting ofhydrogen, saturated alkyl radicals, unsaturated alkyl radicals,substituted aryl radicals and non-substituted aryl radicals, and whereinn is an integer of 1 to 10, (2) cooling the foam, and (3) washing thefoam.

This is a continuation-in-part of our application Ser. No. 332,250,filed Dec. 20, 1963, now abandoned, and the invention relates to amethod of rendering hydrophilic a polyester or polyether basedpolyurethane foam and to the resulting products.

Alveolate foams are particularly suitable for the manufacture of spongesintended for industrial or domestic use. Open cell polyurethane foams,obtained by reacting a polyisocyanate either with a polyester or with apolyether, in most cases have the appearance of natural sponges. Theirmain drawback in relation with the latter or to regenerated cellulosesponges is that their water absorption capacity is very slight.

An object of the invention is to overcome this drawback of polyurethanefoams. The invention accordingly provides a method of renderinghydrophilic a polyester or polyether based polyurethane foam, saidmethod comprising:

(1) Reacting at a temperature of from about 70 C. to 110 C., in thepresence of a catalyst selected from the group consisting of potassiumhydroxide, sodium hydroxide, potassium chloride, potassium acetate,potassium phenolate, potassium methylate and potassium isopropylate,

(a) a polyether or polyester based polyurethane foam,

and (b) at least one carboxylic hydroxyacid lactone having the generalformula:

o[o(R3)21..-c=o

Rz -o wherein R and R and R are selected from the group consisting ofhydrogen, saturated alkyl radicals, unsaturated alkyl radicals,substituted aryl radicals and non-substituted aryl radicals and whereinn is an integer of l to 10,

(2) Cooling said foam and (3) Washing said foam The method according tothe invention thus consists in rendering polyurethane foam, or a spongeprepared from said foam, hydrophilic by adding hydrophilic molecules tothe reactive groups of the foam, chemically fixing said molecules andlengthening the chain by polyaddition of said molecules. This may, forexample, be achieved by impregnating the foam with a solution of thelactone and of the catalyst in an inert solvent, by then eliminatingexcess solution and by heating the impregnated foam at the desiredtemperature for the length of time required for the reaction.

It should be noted that the same meaning is given in this text to thephrases polyurethane foam and polyurethane sponge.

Lactone of the above general formula may for example bebeta-propiolactone or gamma-butyrolactone or a mixture thereof.

As regards the inert solvent, any one of the following solvents may beused: benzene, acetone, ortho-xylene, meta-xylene or a mixture thereof,tetra-hydronaphthalene and tetrachloromethane.

As for the temperature of the reaction, which can range from 70 to 110C., the best results are achieved with a temperature of about C.

It should be noted that the method according to the invention can beapplied on any known polyether or polyester based polyurethane foam, thebest results being obtained with open-cell, flexible foams. The methodsof making the polyurethane foams or sponge to be treated form no part ofthe present invention and are well known and widely described in patentsas well as other literature, for instance German Plastics Practice by DeBell et al., 1946.

The method may for example be carried out in the following manner:

Example 1 A polyether based open-cell polyurethane foam was made bymixing parts of polypropylene-glycol with parts of a mixture of 80 molespercent 2,4 tolylene diisocyanate and 20 moles percent 2,6 tolyenediisocyanate, 0.4 parts of stannous oct-oate, 1 part of silicone oil SF1066, 0.2 part hexamethylene diamine and 3.6 parts water and thenvigorously stirring the mixture for 15 seconds, pouring it into a moldwherein it foamed, the foam being complete after 10 minutes and thenallowing to cure at 80 C. overnight, SF 1066 is a stable copolymer of adimethylpolysiloxane and a polyoxyalkylene ether. The polyether basedpolyurethane foam (or a polyurethane sponge) obtained was impregnatedwith a mixture consisting of 100 ml. of a 2% solution of potassiumisopropylate in isopropyl alcohol, 350 ml. of xylene and 350 ml. ofbeta-propiolactone. After elimination of excess solution, theimpregnated foam was heated in an oven at a temperature of 80 C. for onehour. The foam was then left to cool and washed.

Example 2 The same procedure was adopted as in Example 1, but with amixture consisting of 20 ml. of a 2% solution of potassium isopropylatein isopropyl alcohol, 70 ml. of beta-propiolactone and 630 ml. ofxylene.

Example 3 The procedure was the same as in Example 1, but the mixtureconsisted of ml. gamma-butyrolactone, 150 ml. of acetone and 50 ml. of a2% solution of potassium isopropylate in isopropanol.

3 Example 4 100 parts of a polyester obtained from 1 mole of adipic acidand 1.2 moles of diethylene glycol were mixed with 3 parts ofmethyl-diethanolamine and 2 parts of water. Thereupon 35 parts oftolylene diisocyanate were added and the mixture stirred. Afterhardening an elastic odorless foamed product was obtained.

The polyester based polyurethane foam so obtained was impregnated as inthe preceding examples but with a mixture of 100 ml.gamma-butyrolact-one, 300 ml. of xylene and 30 ml. of a 2% solution ofpotassium isopropylate in isopropyl alcohol.

Example 5 As in Example 4, but with a mixture of 50 ml. of a 2% solutionof potassium isopropylate in isopropyl alcohol, 100 ml. ofbeta-propiolactone and 300 ml. of tetrahydronaphtalene.

Example 6 As in Example 5, but by replacing the 300 ml. oftetrahydronaphtalene with 300 ml. of tetracbloromethane.

The method according to the invention may also be carried out in twostages. In the first stage, the foam is impregnated with a solution ofthe catalyst, the excess solution is eliminated and the foam is, dried.In the second stage, the foam, upon which the catalyst has previouslybeen deposited, is impregnated with a lactone solution and is heatedafter elimination of excess liquid. The washing is carried out aftercooling as before.

By way of catalyst solvent, isopropanol may be used as in the aboveexample, or else water or methanol.

The following examples illustrate the manner in which the methodaccording to this two-stage version may be carried out.

Example 7 The same foam as in Example 1 is impregnated with a solutionconsisting of 200 ml. of water, 4 g. of potassium chloride and 200 m1.of isopropanol. The excess solution is eliminated and the impregnatedfoam is dried. The foam is again impregnated with a solution consistingof 200 m1. of xylene and 200 ml. of beta-propiolactone whereupon it isheated at a temperature of 80 C. for one hour after removal of excesssolution. The foam then is allowed to cool and is washed.

Example 8 The procedure is the same as in Example 7, but by carrying outthe first impregnation with a solution consisting of 380 ml. of Waterand 8 g. of potassium acetate, and the second impregnation with asolution consisting of 200 ml. of beta-propiolactone and 200 ml. ofxylene.

Example 9 The procedure is the same as in Example 7, but by carrying outthe first impregnation with a solution consisting of 2.3 g. of potassiumhydroxide, 10 ml. of water and 400 ml. of .isopropanol, and the secondimpregnation with a solution consisting of 200 ml. of xylene and 200 ml.of beta-propiolactone.

Example 10 The procedure is the same as in Example 7, but by carryingout the first impregnation with a mixture of 100 ml. of a 2% solution ofpotassium isopropylate in isopropyl alcohol and 700 ml. of isopropylalcohol, and the second impregnation with a solution consisting of 400ml. of xylene and 400 ml. of beta-propiolactone.

Example 11 As in Example 10, but by carrying out the second impregnationwith a solution consisting of 600 ml. of xylene and 200 ml. ofbeta-propiolactone.

Example 12 As in Example 10, but by carrying out the second impregnationwith a solution consisting of ml. of betapropiolactone and 720 ml. ofethyl ether.

Example 13 As in Example 10, but by carrying out the second impregnationwith a solution consisting of 40 ml. of betapropiolactone and 760 ml. ofbenzene.

It is to be noted that in the above examples the potassium isopropylatesolution is prepared from metallic potassium which is caused to reactwith isopropyl alcohol.

The foams that have been treated according to the above examples exhibitremarkable hydrophilic properties. These have been checked by:

(l) A standard method which consists in determining the wetting time ofa sponge, before and after the hydrophilization treatment. It has beenobserved that the wetting time of the sponge before treatment is about 5minutes, whereas the wetting time of the same sponge, once treated, canbe as low as 5 seconds,

(2) A standard method which consists in measuring the capillary rise ofwater in a foam, before and after hydrophilization treatment. This riseis nil in the case of the non-treated foam. It can exceed g./dm. /minutefor the sponge when treated. This capillary rise is comparable to thatobtained with a sponge of regenerated cellulose.

From the above examples, it is seen that the method is relatively fast,calls for no particular technique and can be carried out continuously.The degree of hydrophilization depends of course on the concentration ofthe lactone in the solution with which the foam is impregnated. Ahydrophilic foam can already be obtained with a 1% concentration oflactone. The degree of hydrophilization is set at the start depending onthe use to which the sponges are to be put.

The invention also provides a modified polyester or polyether basedpolyurethane foam which exhibits improved hydrophilic properties ascompared to the unmodified foam, comprising polyester or polyether basedpolyurethane foams having molecules of at least one lactone chemicallybonded in situ on to the reactive groups of the foam.

As it is known, polyurethane foam, either polyester or polyether based,comprise as main structural unit, the urethane group.

The urethane group are capable of being added to the lactone moleculethrough the hydrogen atom.

The hydrophilic polyester or polyether based polyurethane foam producedby the process according the invention comprises lateral chains,obtained by polyaddition of lactone molecule on the urethane group.These lateral chains which impart high hydrophilic properties to thefoam, can be either acid terminated or alcohol terminated, according tothe following general formulae:

where R R R and n have the same meaning as above.

We claim:

1. A method of rendering hydrophilic a polyester or polyether basedpolyurethane foam comprising:

( 1) reacting at a temperature of from about 70 to 110 C. in thepresence of a catalyst selected from the group consisting of potassiumhydroxide, sodium hydroxide, potassium chloride, potassium acetate,potassium phenolate, potassium methylate and potassium isopropylate,

(a) a polyether or polyester based polyurethane foam, and

(b) at least one carboxylic hydroxyacid lactone having the generalformula wherein R R and R are selected from the group consisting ofhydrogen, saturated alkyl radicals, unsaturated alkyl radicals,substituted aryl radicals and non-substituted aryl radicals, and whereinn is an integer of l to 10,

(2) cooling said foam, and

(3) washing said foam 2. The hydrophilic foam produced by the process ofclaim 1.

3. The method as defined in claim 1, wherein the reaction 1) is carriedout a temperature of about 80 C.

4. The method as defined in claim 1, wherein said lactone (b) includesbeta-propiolactone.

5. The method as defined in claim 1, Where said lactone (b) includesgamma-butyrolactone.

6. The method as defined in claim 1, wherein, prior to the reaction (1)said foam is impregnated with a solution comprising said lactone (b),said catalyst, and at least one inert solvent.

7. The method as defined in claim 6, wherein said inert solvent consistsof at least one of the group consisting of ortho-xylene, para-xylene,meta-xylene a mixture of ortho-, para-, and meta-xylene,tetrahydro-naphthalene, tetrachloromethane, acetone, benzene and ether.

8. The method as defined in claim 1, wherein, prior to said reaction(1),

(i) said foam is initially contacted with a first solution comprisingsaid catalyst and a solvent for said catalyst,

(ii) the excess solvent is thereafter eliminated from said foam,

(iii) said foam is then dried, and

(iv) thereafter said foam is impregnated with a second solutioncomprising said lactone (b) and a solvent inert to said foam.

9. The method as defined in claim 8, wherein said catalyst solvent insaid first solution consists of at least one of the group consisting ofwater, isopropanol and methanol.

10. The method as defined in claim 8, wherein said inert solvent in saidsecond solution consists of at least one of the group consisting oforthoxylene, meta-xylene, a mixture of ortho-, paraand meta-xylene,tetrahydronaphthalene, tetrachloromethane, acetone, benzene and ether.

References Cited UNITED STATES PATENTS 2,920,983 1/1960 Bugosh 117-982,965,584 12/1960 Elkin 2602.5 2,990,378 6/ 1961 Hurwitz et a1 2602.52,990,379 6/1961 Young et al 260-2.5 3,149,000 9/1964 Beicos 117983.l69,945 2/ 1965 Hostettler et al 26078.3 3,186,971 6/1965 H-ostettleret al 260-77.5

FOREIGN PATENTS 411,336 11/1966 Switzerland.

417,084 1/ 1967 Switzerland.

924,081 4/ 1963 Great Britain. 1,394,765 3/1965 France. 1,399,243 4/1965France.

DONALD E. CZAJA, Primary Examiner.

F. MCKELVEY, Assistant Examiner.

